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Coastal Vulnerability Index – CVI (2011)

Description

The Coastal Vulnerability Index (CVI) is one of the most commonly used and simple methods to assess coastal vulnerability to sea level rise, in particular due to erosion and/or inundation (Gornitz et al., 1991). The first methodological step for the calculation of the original formulation of CVI deals with the identification of key variables representing significant driving processes influencing the coastal vulnerability and the coastal evolution in general. In general CVI formulation includes 6 or 7 variables; the U.S. Geological Survey (USGS) in particular considered the following six variables: geomorphology, shoreline change rates, coastal slope, relative sea level rate, mean significant wave height, mean tidal range. The second step deals with the quantification of the identified key variables. Although various methodologies are available for this step, quantification is generally based on the definition of semi-quantitative scores according to a 1-5 scale; 1 indicates a low contribution to coastal vulnerability of a specific key variable for the studied area or sub-areas, while 5 indicates a high contribution. Afterwards (third step) key variables are aggregated in a single index, through a mathematical formula. Finally as a fourth step CVI values are then classified in n different groups (usually 3 or 4) using n-1 percentiles as limits. Although widely used, the greatest limitation of the original CVI formulation is its incapacity to address socio-economic aspects (such as for example number of people affected, infrastructure potentially damaged and economic costs) within the assessment of coastal vulnerability (Gornitz et al., 1993; Cooper and McLaughlin, 1998; ETC-ACC, 2010). To deal with this main limitation, two main possible approaches are available: (i) use of the original CVI in association with other indexes able to more properly represent the complexity of the coastal system also in relation to socio-economic aspects; (ii) modify/extend the original formulation of the CVI also taking into account variables representing the socio-economic systems. This second approach led to the development of various improved formulation, including the following ones: Özyurt et al. (2008) developed a CVI to specifically assess impacts induced by sea level rise. The index is determined through the integration of 5 sub-indices, each one corresponding to a specific sea level rise related impact; i.e. coastal erosion, flooding due to storm surges, permanent inundation, salt water intrusion to groundwater resources and salt water intrusion to rivers/estuaries. Each sub-index is calculated through the semi-quantitative assessment of both physical and human influence parameters. The author applied this methodology to the Göksu Delta in Turkey. Szlafsztein and Sterr (2007) formulated the composite vulnerability index that combines a number of separate variables reflecting natural and socio-economic characteristics that contribute to coastal vulnerability due to natural hazards. The authors applied the index to the Brazilian coastal areas, considering these natural parameters: coastline length and sinuosity, coastline density into municipal areas, coastal feature (estuarine, beach etc.), coastal protection measures, fluvial drainage, flooding areas. Socioeconomic parameters consisted in: total population and total population affected by floods, population density, non-local population (i.e. born elsewhere but living in considered areas), poverty, municipal wealth. McLaughlin and Cooper (2010) developed a multi-scale CVI, specifically addressing erosion impacts. The index integrates three sub-indices: (i) a coastal characteristic sub-index, describing the resilience and coastal susceptibility to erosion, (ii) a coastal forcing sub-index, characterising the forcing variables contributing to wave-induced erosion, (iii) and a socio-economic sub-index, describing targets potentially at risk. In particular, the authors applied the index to a multi-scale system, including: Northern Ireland (national scale), Coleraine Borough Council (regional scale) and Portrush east Strand (local scale).

Reference information

Websites:
Source:
Various, see http://cca.eionet.europa.eu/reports/1 (ETC-CCA)

Keywords

Vulnerability assessment, coastal area, index, multi-scale approach

Climate impacts

Sea Level Rise

Elements

Vulnerability Assessment

Sectors

Coastal areas

Geographic characterisation

Global

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